Elastic positively-charged liposomes for topical administration of acyclovir

Elastic positively-charged liposomes of soya lecithin were prepared using sucrose monopalmitate as deforming agent, and l-alanine benzyl ester or stearylamine as cationic charge-inducing agent. The positive charge of the liposomes was confirmed by zeta potential measurements and their elasticity by filtration through microporous filter. Positively-charged liposomes had a higher acyclovir entrapment efficiency than negatively-charged liposomes. Elastic positively-charged liposomes containing acyclovir, applied non-occlusively to pig-ear skin, determined a skin flux similar to that of non-elastic positively-charged liposomes, prepared using soya lecithin, cholesterol and stearylamine, but higher than that of non-elastic negatively-charged liposomes or control suspension. Skin deposition of acyclovir from elastic positively-charged liposomes was higher (up to 600 nmol/cm2) than that from non-elastic positively- or negatively-charged liposomes (respectively 344 nmol/cm2, 237 nmol/cm2) and than that from elastic negatively-charged liposomes (435 nmol/cm2). The enhanced ACV accumulation within the skin obtained with elastic positively-charged liposomes might help to optimize drug targeting, creating new opportunities for well-controlled, modern, topical application of ACV in the treatment of Herpes simplex.